duct systems checklist

HVCA Checklist 1

INSPECTION CHECKLIST

DUCTWORK SYSTEMS

Checklist DW1 – Sheet metal ductwork - General

Note: Analysis of the requirements of DW/144 and related documents does not suggest majordifferences in the basic installation of pre-made rectangular, circular and flat oval duct and fittings.

All items marked non-compliant (NC) must be explained on the “Non-compliance Report”

Item Requirement Source doc OK NCGeneral

1. Ductwork layout drawings should be available at all times onsite

2. Operatives should have access on site to DW144 “Specificationfor sheet metal ductwork”

DW/144

3. Duct work sections should be unloaded and stored on site insuch a way as to avoid damage and contamination

DW/144 Appendix C

Health and Safety

4. Operatives should follow the Health and Safety at work policyof their employer. In all cases, sealant materials must be applied strictly inaccordance with the manufacturer’s instructions and COSHHassessment carried out. Only an approved type of sealant, gasket or tape shall be usedby the contractor

DW/144section 8.2.1 JS21 & JS21A

Assembly of Ductwork Sections on Site

5. Rectangular Ducts: Cross joints should be sealed in accordance with Figs 10,13&14 Fastenings and maximum spacings should be in accordancewith section 10.7

DW144section 10.4.2 DW144section 10.7

6. Circular Ducts: Spirally wound and straight seamed cross joints should besealed in accordance Figs32-45 Fastenings and maximum spacings should be in accordancewith section 13.3


7. Flat Oval Ducts: Spirally wound and straight seamed cross joints should besealed in accordance with Figs 53-63 Fastenings and maximum spacings should be in accordancewith section 16.4.


8. Inspector to check assembly of cross joints of duct ininaccessible places eg where it duct is installed against awall.(Inspection can be carried out by use of a small mirror onthe end of a stick.)

9. Partially completed ductwork must be temporarily sealed offand supported as necessary for safety and to avoid undue stress

HVCA Checklist 2

on fixings, hangers and joints. Access/Inspection openings

10. All openings should be made safe and have sealed accesspanels/covers which can be speedily removed and replaced.Self piercing screws are not acceptable.

DW144section 20.1

11. There should be no external obstructions to preventing apanel/cover from being removed

Checklist DW2 – Sheet metal ductwork – Hangers and support

Item Requirement Source doc OK NC

1. The fixing to the building structure should of a strength anddurability compatible with the ductwork support attached to it.A fixing to concrete or brickwork must be made in such a waythat it cannot be loosen or pull out through normal stressing ornormal changes in the building structure.

DW144Section 19.2

2. Hangers for horizontal ductwork should be of an appropriatematerial galvanised steel rod or studding or flat strap orstranded wire

DW144Section 19.3.1

3. Projection of a rod or studding hanger through the bottombearer should, where practicable not exceed twice the thicknessof the securing nut.

DW144Section 19.3.1

4. Duct bearing member for horizontal ductwork should be inaccordance with section 19.3.1

DW144Section 19.3.1

5. Hangers, supports and distance between supports forrectangular, flat oval and circular ducts should be in accordancewith table 15 of DW/144

DW144 Table15

6. Duct hangers should be fixed to avoid torsion on the ductwork.

Vertical Ducts

7. The installation of vertical ducts exceeding 4 metres in lengthmust comply with the designers requirements (checkinstallation drawings)

DW144section 19.4

8. Vertical ducts should be adequately supported from thestiffened angle or the angle frame, or by separate supportingangles fixed to the duct

DW144section 19.4

Heavy Loadings and larger ducts

9. Duct support must take into account any addition loads imposedon the duct by attached equipment

DW144section 19.5

Insulated ducts with vapour sealing

10. Vapour sealing around the hanger may be required where thetemperature of the air in the duct is low enough to promotecondensation on external surfaces (to be specified by thedesigner – check installation details)

DW144section 19.6

Checklist DW3 – Sheet metal ductwork – Fire and Smoke Dampers


1. Installation of fire and smoke dampers should be in accordancewith DW/TM3 and manufacturers guidance

DW/TM3

2. Access panels should be provided to give access to fire and DW 144

HVCA Checklist 3

smoke dampers for inspection and servicing section20.2.1.1

Checklist DW4 – Sheet metal ductwork – Miscellaneous

Item Requirement Source doc OK NCFlexible ducts

1. Fastenings for flexible metal ducts should be as for rigidcircular ducts DW 144 section 13.3 & Table 9. Sealing shouldbe as section 8.

DW144section 25.2.1

2. Flexible fabric ducts should be fastened at each end using aproprietary band without causing damage. The airtightness ofthe system should be maintained.

DW 144section 25.2.2

3. Flexible ducts should be supported without excessive saggingand kinking

DW 144section 25.3

Flexible Joint Connections

4. Flexible joint connections should be in accordance with fig.80DW144. The effective length of the unsupported material shallbe 50mm (minimum) –250mm (maximum)

DW 144sections 26.1& 26.3

5. Joint connections used at building expansion joints and faninlet/outlets should be aligned correctly and should not be taunt

6. With flanged rectangular connections, the flexible materialshall be held in place with flat bar strips of not less than 2 mmthick attached to the flanges using suitable fixings.

DW144section 26.4

7. Connections to circular and oval ducts should follow therequirements in section 26.5 & 26.6 DW144

DW144sections 26.5& 26.6

Connections to Building Openings

8. Ductwork connections to building openings shall have a flangeof suitable profile to permit practical fixing to the openingframe. Gasket strip or sealer shall be applied between theflange and building opening frame.

DW144section 28.2

Checklist DW5 – Sheet metal ductwork – Testing


1. General: Air leakage testing is mandatory for high-pressure ductwork.Testing should be in accordance with the procedures laid downin DW/143. No such testing is required for low or mediumpressure ductwork unless specified by the client. The testshould be carried out as the work proceeds and prior to theapplication of thermal insulation.

DW/143

2. For the purposes of testing the contractor should have thefollowing: DW/143 “ A practical Guide to Ductwork LeakageTesting”, Test apparatus and instrumentation as specified inDW143

3. Is there compliance with test methodology DW143

4. Are the results of the air leakage rate within the acceptablelimits

DW/143Table1

HVCA Checklist 4

Checklist DW1 – Plastics ductwork - General

Note: Analysis of the requirements of DW/154 and related documents does not suggest majordifferences in the basic installation of pre-made rectangular and circular ducts and fittings.


1. Ductwork layout drawings should be available at all times insite

-

2. Operatives should have access on site to DW154 “Specificationfor plastics ductwork”

DW/154

3. Duct work sections should be unloaded and stored on site insuch a way as to avoid damage and contamination

DW/144 Appendix C

Health and Safety

4. Operatives should follow the Health and safety at Work policyof their employer. In all cases, sealant materials must be applied strictly inaccordance with the manufacturer’s instructions and COSHHassessment carried out. Only an approved type of sealant, gasket or tape shall be usedby the contracto

DW/154section 8.2 JS21 & JS21A

Assembly of Ductwork Sections on Site

5. Rectangular Ducts Flanged cross joints for UPVC and PP rectangular duct sectionsshould be sealed using a manufacturers approved type ofsealant or gasket. Rectangular UPVC and PP socket and spigot cross joints shouldbe sealed by continuous hot air welding and follow procedure8.2.3 in DW154

DW154figures 3 and 4 DW154Section 8.2.3and figure 1

6. Circular Ducts Flanged cross joints for UPVC and PP circular duct sectionsshould be sealed using a manufacturers approved type ofsealant or gasket. Circular UPVC socket and spigot cross joints or sleeve jointsshould be sealed by either solvent cementing or continuous hotair welding and follow requirements 8.2 in DW 154

DW154 figure 12 DW154section 8.2.

7. Inspector to check assembly of cross joints of duct ininaccessible places eg where it duct is installed against a wall.(Inspection can be carried out by use of a small mirror on theend of a stick.)

8. Partially completed ductwork must be temporarily supported asnecessary for safety and to avoid undue stress on fixings,hangers and joints

Access/Inspection openings

9. All openings should be made safe and have sealed accesspanels/covers which can be speedily removed and replaced.Self piercing screws are not acceptable.

DW154section 20 andDW/144 Part 7Section 20

10. There should be no external obstructions to preventing a

HVCA Checklist 5

panel/cover from being removed

Checklist DW2 – Plastics ductwork – Hangers and support


1. The fixing to the building structure should of a strength anddurability compatible with the ductwork support attached to it.A fixing to concrete or brickwork must be made in such a waythat it cannot be loosen or pull out through normal stressing ornormal changes in the building structure.

DW144Section 19.2

2. Rectangular Ducts Hangers and supports for un-reinforced rectangular horizontalductwork should be in accordance with table 8 of DW154 Circular Ducts Hangers and supports for un-reinforced circular horizontalductwork should be in accordance with table 9 of DW154

DW154Section 14.2 DW154section 14.3

3. Projection of a rod or studding hanger through the bottombearer should, where practicable not exceed twice the thicknessof the securing nut.

DW144Section 19.3.1

4. The arrangement of support bears and hangers should be inaccordance with figs 14-22 DW145

DW145Section 14

Vertical Ducts

5. Vertical ducts should be supported at 4 metres intervals. Orwhere they pass through a floor. The supports should notexceed 4.5 metres intervals.

DW154section 14.4

6. Vertical ducts should be adequately supported from thestiffened angle or the angle frame, or by separate supportingangles fixed to the duct. See figures 17 and 18 DW154

DW154section 14.4

External ducts

7. Ducts external to buildings must be adequately supported inaccordance with the designers requirements

DW154section 14.5

Checklist DW3 – Plastics ductwork – Fire dampers and intumescent sleeves


1. Installation of fire dampers and intumescent sleeves should bein accordance with DW/TM3 and manufacturers guidance.COSHH assessment should be undertaken.

DW/TM3 JS 21 & JS21A

2. Access panels should be provided to give access to fire andsmoke dampers for inspection and servicing

DW 144 Section20.2.1.1

Checklist DW4 – Plastics ductwork – Miscellaneous


Flexible/expansion joint connections1. Flexible/expansion joints when incorporated should be aligned DW154

HVCA Checklist 6

correctly during installation and maintain the air tightness of thesystem

Section 18.1

2. The minimum effective length of a flexible joint shall be 50mm. In no case shall a flexible joint exceed 250mm.

DW154 Section 18.3

3. With flanged rectangular and spigot connections, the flexiblematerial shall be held in place with flat plastic strips of not lessthat 6 mm thick

DW154Section 18.4

4. With flanged circular connections the flexible material shall beheld in place with flat plastic backing strips or proprietary clipbands with screw or toggle fastener

DW 154Section 18.5

5. For rectangular and circular ducts where the parent and flexiblematerial are from similar based product, they can be joined tothe duct using the welding method described in DW154 section8.2.3

DW 154 Section 8.2.3

Connections to Building Openings

6. Ductwork connections to building openings shall have a flangeof suitable profile to permit practical fixing to the openingframe. Gasket strip or sealer shall be applied between theflange and building opening frame.

DW154 Section 20.2

7.

Checklist DW5 – Plastics ductwork – Testing


1. General: Air leakage testing is mandatory for high-pressure ductwork.Testing should be in accordance with the procedures laid downin DW/143. No such testing is required for low or mediumpressure ductwork unless specified by the client or designer.The test should be carried out as the work proceeds and prior tothe application of thermal insulation.

DW/143

2. For the purposes of testing the contractor should have thefollowing: DW/143 “ A practical Guide to Ductwork LeakageTesting”, Test apparatus and instrumentation as specified inDW143

3. Is there compliance with test methodology DW143

4. Are the results of the air leakage rate within the acceptablelimits

DW/143Table1

duct systems checklist

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